JPS624676Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a gas fuel engine that automatically adjusts the air-fuel ratio or excess air ratio of the gas fuel engine.

In gas fuel engines, especially electrically ignited gas fuel engines, it is essential to optimize the air-fuel ratio as a means to avoid knock and misfire regions and to improve fuel consumption and exhaust gas characteristics. It is.

Conventional techniques related to such adjustment devices generally do not include a control device, but use mechanical means such as providing a fuel throttle section that is linked to a butterfly that senses the dynamic pressure caused by the air flow in the mixer section.

On the other hand, the air-fuel ratio, which avoids the knocking and misfire range and also takes into account the minimum fuel consumption and exhaust gas, generally does not have a simple linear relationship with the load factor, and the vertical axis in Figure 2 shows the gas amount. The pressure regulating valve opening and the throttle valve opening are expressed on the horizontal axis as a knocking region, a misfire region or stall region, and a fuel efficiency deterioration region.

However, the above-mentioned conventional technology does not achieve this objective because it uses mechanical means. Another problem was that it was difficult to make adjustments.

In addition, as another general conventional technology, there is a method such as installing an oxygen concentration sensor at the outlet of the combustion chamber and adjusting the amount of fuel supplied based on the detection result, but the oxygen concentration sensor used here They are expensive and have a durability of only a few hundred hours, and they also have many disadvantages such as the fact that their output changes significantly depending on the temperature during use, and they require high control circuit costs and frequent replacement. There was a problem that the cost burden was large.

Therefore, the present invention was made to solve the problems of the conventional technology, and provides a gas fuel engine with a control device that avoids the knock region and misfire region and improves the fuel consumption rate and exhaust gas characteristics. It is intended to.

That is, the control device for a gas fuel engine of the present invention is applicable to a gas fuel engine having a governor mechanism that maintains a constant speed by increasing or decreasing the opening degree of a throttle valve. means for detecting the opening degree of each throttle valve, means for storing the possible opening coefficients of the opening degree of the throttle valve and the opening degree of the gas amount adjusting valve in the form of a numerical table, and means for manually setting constants. At the same time, the opening degree of the throttle valve is detected as appropriate, and the possible opening degree of the gas amount adjusting valve selected based on the above numerical table plus the constant according to the above manual, and the gas It is constructed by providing arithmetic control and output means that can increase or decrease the opening degree of the gas amount adjusting valve in order to reduce the difference with the detected value of the opening degree of the gas amount adjusting valve.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A control device according to an embodiment of the present invention will be described below with reference to the drawings.

First, FIG. 1 is a conceptual system diagram showing a gas fuel engine according to an embodiment of the present invention. Fuel gas 22 supplied to the combustion chamber of the engine 20 is first mechanically connected to an electric motor 12 by a lever 14. The gas then reaches the mixer 15 via the driven gas amount adjustment valve 11 . Further, air 23 is taken into this mixer 15 from another port, mixed, and then passed through a throttle valve 16 to reach the combustion chamber of the engine 20.

Here, in the present invention, as a prerequisite technology, it is assumed that the throttle valve 16 is controlled by the governor mechanism 18 and is adjusted to a valve opening degree that can always maintain the rotational speed of the engine 20 constant. Although this governor mechanism 18 is outside the scope of the present invention, any method may be used, such as applying an electronic governor that operates in response to a signal from the engine rotational speed detector 21 to the governor mechanism 18.

Next, 13 is an opening detector for the gas amount adjustment valve 11, and 17 is an opening detector for the throttle valve 16, both of which can be provided with known technology such as a potentiometer. can.

The opening degree of the throttle valve 16 and the gas amount adjustment valve 11
As shown in this embodiment, a microcomputer system can be used as the means for storing the possible relationship between the two in the form of a numerical table and the arithmetic control means.

That is, 2 in Figure 1 is the CPU, 3 is the ROM,
Here, an arithmetic control program and possible values of the gas regulating valve 11 can be stored in the form of a numerical table. 4 is a RAM, and 5 is an I/O interface.

Note that each of the units shown in 2 to 5 above can not only be constructed from discrete LSIs. A one-chip microcomputer like Block 1 has similar functions. Further, 8 indicates a so-called system bus line consisting of a data bus, an address bus, and a control bus.

Furthermore, since the values detected by the two opening degree detectors 13 and 17 are detected as analog values, a multiplexer and an A/D converter 6 are required, which can also be connected to the system bus line 8. .

In addition, the calculation result is the I/O interface 5
When the electric motor 12 is used, the output is output as an opening increase/decrease signal of the electric gas amount adjustment valve 11, and the output is the forward and reverse rotation signals 10,
It is output as 9, which is a power transistor,
Alternatively, connection can be made via an amplifier 7 using a relay or the like.

Furthermore, 24 in FIG. 1 is a setting device that is a means for setting the constant A, and for example, a manually operated potentiometer can be used for this, and the multiplexer and A/D converter described above can be used. It can be read via 6.

It should be noted that it is also possible to employ a digital switch as another means for this setting means. It can perform the same function as the example.

To explain the operation of the control device of the present invention based on the above configuration, first, the opening degree of the throttle valve 16 is adjusted to suit a gas fuel engine for a generator set, etc., which is operated at a constant speed, which is the premise of the present invention. can be used as a substitute characteristic value for the load factor.

Further, the opening degree of the gas amount regulating valve 11 can be used as a substitute characteristic value indicating the magnitude of the air-fuel ratio.

In a gas fuel engine, in order to avoid the misfire region or knocking region, it is necessary to adjust the air-fuel ratio to a predetermined value, and that value varies depending on the load factor, and the above-mentioned second The figure is a graph of the situation, and it can be set as one possible control line 31, taking into consideration fuel consumption and exhaust gas level in addition to the above-mentioned avoidance range.

One of the features of the present invention is to memorize this control line 31, and the reason why the control line 31 is step-shaped is for quantization when converting into a numerical table. Needless to say, the larger the storage capacity is, the more fine-grained control lines 31 can be stored.

According to experimental results, when the fuel gas components change or when the engine 20 changes over time, the misfire region and knocking region shown in FIG. 2 change in a substantially vertically shifted manner.

However, in the present invention, the numerical table can be manually shifted up or down from outside the device using the sequence described below, so it is sufficient to create and memorize the numerical table based on the new engine 20 and the typical gas component calorific value. This point is one of the important features of the present invention.

In addition, as a method of adjusting the constant A, for example, engine 2
This can be done by, for example, setting the setting device 24, which is the means for setting the constant A, to a position immediately before the engine 20 knocks while operating the engine 0 in a high load range.

Next, the control logic is as shown in the flowchart of Fig. 3, but it should be noted here that the detected value of the opening degree of the gas amount adjustment valve 11 is compared with the target value according to the numerical table. In this case, it is effective to specify a certain allowance balance α to prevent chattering.

In addition, the interval must be selected at an optimal value that does not cause frequent control overshoots in consideration of the rotational angular velocity of the electric motor 12, and the interval itself must be set using a software timer or an external clock. It is possible to adopt this method.

Furthermore, to illustrate some other embodiments other than the embodiments of the present invention that are applicable to the present invention, the electric motor 12 in FIG.
For example, it is possible to use a servo solenoid,
In this case, the output from the control circuit is an analog value, so by assigning the number of bits corresponding to a predetermined precision to the output section of the I/O interface 5 and outputting it via a D/A converter (not shown). It is achievable.

In addition, in the present invention, mixer 1 is used as a control output.
Although the opening degree of the gas amount adjusting valve 11 at the front stage of FIG. In this case, the numerical table pattern shown in FIG. 2 would be appropriate.

Furthermore, it goes without saying that a similar sequence circuit can be constructed using ordinary random logic without using the CPU 2 as a control circuit.

Note that when the opening degree of the gas amount regulating valve 11 is changed by the control device of the present invention, it may cause a change in the rotational speed of the engine 20, but this can be immediately corrected by a separately provided governor mechanism. It is.

Therefore, if the control device of the present invention is applied to a gas fuel engine, the optimal air-fuel ratio pattern for the load factor is stored in the form of a numerical table, so any pattern can be adopted, and as a result, the misfire region and knock region Optimum patterns that have been tested and confirmed during engine development can be freely set, such as avoiding fuel consumption and minimizing fuel consumption.

In particular, with this invention, numerical values can be changed manually from the outside, so a control device with the same specifications can handle various component gas fuels, and even when the knock range changes little by little due to changes in the engine over time. The manual table correction function is effective.

In addition, since the opening of the throttle valve is detected as a substitute characteristic for the load factor, the device is inexpensive, and unlike load detection methods such as torque sensors, the installation location is restricted depending on the type of load. The advantage is that there is no need to worry about

Furthermore, since the control device of the present invention does not measure the air-fuel ratio itself, there is no need for an expensive and difficult-to-handle sensor such as an oxygen concentration sensor. Because it uses a numerical table storage system, it has quick response and fewer problems such as hunting.

As described above, the control device of the present invention has a simple mechanism, is low in price, and is easy to adjust and maintain. Enables air-fuel ratio control in any pattern and avoids knock-out and misfire areas.
This enables more reliable engine control and minimizes fuel consumption, exhaust gas, etc.

Note that the present invention can be effectively applied to gas fuel engines in general that operate at a constant speed.

[Brief explanation of the drawing]

Fig. 1 is a conceptual system diagram showing a gas fuel engine in an embodiment of the present invention, and Fig. 2 is a control of the gas fuel engine shown in Fig. 1 in relation to the gas amount adjustment valve opening and throttle valve opening of the gas fuel engine. FIG. 3 is a flowchart of the control device for the gas fuel engine shown in FIG. 1. 1...Block, 2...CPU, 3...ROM,
4...RAM, 5...I/O interface,
6...Multiplexer, A/D converter, 7
...Amplifier, 11...Gas amount adjustment valve, 13...Opening degree detector, 15...Mixer, 16...Throttle valve, 17...Opening degree detector, 18...Governor mechanism, 20...Engine, 21... Engine rotation speed detector, 24... Enactment device, 31... Control line.

Claims (1)

[Scope of utility model registration request] In a gas fuel engine having a governor mechanism that maintains a constant speed by increasing/decreasing the opening of a throttle valve, there is provided an opening detecting means for each of the gas amount adjusting valve provided in the front stage of the mixer, the throttle valve provided in the rear stage of the mixer, and the throttle valve. Means for storing the possible opening coefficients of the opening of the valve and the opening of the gas amount adjustment valve in the form of a numerical table, and means for manually setting constants, and detecting the opening of the throttle valve as appropriate. However, the difference between the possible opening degree of the gas volume adjustment valve selected based on the above numerical table plus the constant according to the manual and the detected opening value of the gas volume adjustment valve is reduced. A control device for a gas fuel engine, characterized in that it is provided with arithmetic control and output means that can increase or decrease the opening degree of the gas amount regulating valve.